The present invention is related to methods and systems for accessing, diagnosing and treating target tissue regions within the middle ear and the Eustachian tube.
Referring to FIGS. 1-2, the ear 10 is divided into three parts: an external ear 12, a middle ear 14 and an inner ear 16. The external ear 12 consists of an auricle 18 and ear canal 20 that gather sound and direct it towards a tympanic membrane 22 (also referred to as the eardrum) located at an inner end 24 of the ear canal 20. The middle ear 14 lies between the external and inner ears 12 and 16 and is connected to the back of the throat by a Eustachian tube 26 which serves as a pressure equalizing valve between the ear 10 and the sinuses. The Eustachian tube 26 terminates in a distal opening 28 in the nasopharynx region 30 of the throat 32. In addition to the eardrum 22, the middle ear 14 also consists of three small ear bones (ossicles): the malleus 34 (hammer), incus 36 (anvil) and stapes 38 (stirrup). These bones 34-38 transmit sound vibrations to the inner ear 16 and thereby act as a transformer, converting sound vibrations in the canal 20 of the external ear 12 into fluid waves in the inner ear 16. These fluid waves stimulate several nerve endings 40 that, in turn, transmit sound energy to the brain where it is interpreted.
The Eustachian tube 26 is a narrow, one-and-a-half inch long channel connecting the middle ear 14 with the nasopharynx 30, the upper throat area just above the palate, in back of the nose. The Eustachian tube 26 functions as a pressure equalizing valve for the middle ear 14 which is normally filled with air. When functioning properly, the Eustachian tube 26 opens for a fraction of a second periodically (about once every three minutes) in response to swallowing or yawning. In so doing, it allows air into the middle ear 14 to replace air that has been absorbed by the middle ear lining (mucous membrane) or to equalize pressure changes occurring on altitude changes. Anything that interferes with this periodic opening and closing of the Eustachian tube 26 may result in hearing impairment or other ear symptoms.
Obstruction or blockage of the Eustachian tube 26 results in a negative middle ear pressure 14, with retraction (sucking in) of the eardrum 22. In adults, this is usually accompanied by some ear discomfort, a fullness or pressure feeling and may result in a mild hearing impairment and head noise (tinnitus). There may be no symptoms in children. If the obstruction is prolonged, fluid may be drawn from the mucous membrane of the middle ear 14, creating a condition referred to as serous otitis media (fluid in the middle ear). This occurs frequently in children in connection with an upper respiratory infection and accounts for the hearing impairment associated with this condition.
A lining membrane (mucous membrane) of the middle ear 14 and Eustachian tube 26 is connected with, and is the same as, the membrane of the nose 42, sinuses 44 and throat 32. Infection of these areas results in mucous membrane swelling which in turn may result in obstruction of the Eustachian tube 26. This is referred to as serous otitis media, i.e. essentially a collection of fluid in the middle ear 14 that can be acute or chronic, usually the result of blockage of the distal opening 28 of the Eustachian tube 26 which allows fluid to accumulate in the middle ear 14. In the presence of bacteria, this fluid may become infected, leading to an acute suppurative otitis media (infected or abscessed middle ear). When infection does not develop, the fluid remains until the Eustachian tube 26 again begins to function normally, at which time the fluid is absorbed or drains down the tube into the throat 32 through the Eustachian tube opening 28.
Chronic serous otitis media may result from longstanding Eustachian tube blockage, or from thickening of the fluid so that it cannot be absorbed or drained down the Eustachian tube 26. This chronic condition is usually associated with hearing impairment. There may be recurrent ear pain, especially when the individual catches a cold. Fortunately, serous otitis media may persist for many years without producing any permanent damage to the middle ear mechanism. The presence of fluid in the middle ear 14, however, makes it very susceptible to recurrent acute infections. These recurrent infections may result in middle ear damage.
When the Eustachian tube 26 contains a build-up of fluid, a number of things will occur. First, the body absorbs the air from the middle ear 14, causing a vacuum to form which tends to pull the lining membrane and ear drum 22 inward, causing pain. Next, the body replaces the vacuum with more fluid which tends to relieve the pain, but the patient can experience a fullness sensation in the ear 10. Treatment of this condition with antihistamines and decongestants can take many weeks to be fully effective. Finally, the fluid can become infected, which is painful and makes the patient feel ill and which may cause the patient not to be able to hear well. If the inner ear 14 is affected, the patient may feel a spinning or turning sensation (vertigo). The infection is typically treated with antibiotics.
However, even if antihistamines, decongestants and antibiotics are used to treat an infection or other cause of fluid build-up in the middle ear 14, these treatments will typically not immediately resolve the pain and discomfort caused by the buildup of fluid in the middle ear 14; i.e. the most immediate relief will be felt by the patient if the fluid can be removed from the Eustachian tube 26.
Antibiotic treatment of middle ear infections typically results in normal middle ear function within three to four weeks. During the healing period, the patient can experience varying degrees of ear pressure, popping, clicking and fluctuation of hearing, occasionally with shooting pain in the ear. Resolution of the infection occasionally leaves the patient with uninfected fluid in the middle ear 14, localized in the Eustachian tube 26.
Fluid build-up caused by these types of infections has been treated surgically in the past. The primary objective of surgical treatment of chronic serous otitis media is to reestablish ventilation of the middle ear, keeping the hearing at a normal level and preventing recurrent infection that might damage the eardrum membrane and middle ear bones.
For example, as shown in FIG. 3, a myringotomy can be performed to relieve fluid in the middle ear 14. A myringotomy is an incision 42 in the eardrum 22 performed to remove fluid in the middle ear 14. A hollow plastic tube 44, referred to as a ventilation tube, is inserted and lodged in the incision 42 to prevent the incision 42 from healing and to ensure ventilation of the middle ear 14. The ventilation tube 44 temporarily takes the place of the Eustachian tube 26 in equalizing the pressure in the middle ear 14. The ventilation tube 44 usually remains in place for three to nine months during which time the Eustachian tube 26 blockage subsides. When the tube 44 dislodges, the eardrum 22 heals; the Eustachian tube 26 then resumes its normal pressure equalizing function.
Another method of relieving the pressure in the middle ear 14 is shown in FIG. 4 in which a hypodermic needle 46 is driven through the eardrum 22 through which any accumulated fluid can be withdrawn from typically only the upper portion of the Eustachian tube 26.
The methods of FIGS. 3 and 4 involve rupturing the eardrum 22 to relieve the fluid accumulation and pressure increase in the middle ear. Neither of these methods, in addition to the sometimes permanent puncture created in the eardrum 22, is especially effective in removing all of the fluid in the Eustachian tube 26 since often the lower end 28 thereof is blocked and dammed with fluid.
In connection with the above surgical treatments of FIGS. 3 and 4, Eustachian tube 26 inflation is also employed to relieve the pressure build-up and fluid accumulation as shown in FIG. 5. The hypodermic syringe 46 (shown with a flexible tip 48) is inserted into a nostril or into the mouth until the tip 48 is positioned adjacent the distal opening 28 of the Eustachian tube 26 in the nasopharynx region 30 of the throat 32. Air is blown through the tip 48 via the syringe 46 into the obstructed Eustachian tube 26 and, thus, into the middle ear 14 to help relieve the congestion and reestablish middle ear ventilation. This procedure is often referred to as politzerization. Politzerization is most effective when one of the nostrils is pinched shut (as shown in FIG. 6), while the patient simultaneously swallows. This forces air into the Eustachian tube 26 and the middle ear 14. This technique is good for opening the Eustachian tube 26 but it does not clear accumulated fluid away.
Another method for clearing the middle ear 14 (at least temporarily) is referred to as the “valsalva” maneuver, accomplished by forcibly blowing air into the middle ear 14 while holding the nose, often called popping the ear. This method is also good for opening the Eustachian tube 26 but it does not clear the accumulated fluid away either.
Typical disorders associated with the middle ear and the Eustachian tube include perforated ear drums, tympanosclerosis, incus erosion, otitis media, cholesteotoma, mastoiditis, patulous Eustachian tube, and conductive hearing loss. To treat some of these disorders, ear surgery may be performed. Most ear surgery is microsurgery, performed with an operating microscope. Types of ear surgery include stapedectomy, tympanoplasty, myringotomy and ear tube surgery.
One of the simplest ear surgeries is the myringotomy or the incision of the ear drum. However, ear surgery can also require the removal of the tympanic membrane for the visualization of the middle ear space. Often surgeons will try to preserve the integrity of the membrane by making incisions in the skin of the ear canal and removing the tympanic membrane as a complete unit. Alternatively, middle ear access is achieved via the mastoids. This method approaches the middle ear space from behind the ear and drills through the mastoid air cells to the middle ear. Whether the bony partition between the external ear canal and the mastoid is removed or not depends on the extent of the disease. Canal-wall-down refers to the removal of this bony partition. Canal-wall-up refers to keeping this bony partition intact. The term modified radical mastoidectomy refers to an operation where this bony partition is removed and the eardrum and ossicles are reconstructed. A radical mastoidectomy is an operation where this bony partition is removed and the ear drum, malleus and incus bones are permanently removed so that the inner lining of the large cholesteotoma sac can be safely cleaned. This operation is done when an extensive cholesteotoma is encountered or one that is adherent to the inner ear or facial nerve.
Afflictions of the middle ear and Eustachian tube are very prevalent and a serious medical problem, afflicting millions of people and causing pain, discomfort and even hearing loss or permanent ear damage. Although a number of treatments have been developed, as described above each of them has shortcomings. Therefore, a need exists for improved methods and systems for accessing, diagnosing and treating target tissue regions within the middle ear and the Eustachian tube. Ideally, such methods and systems would be minimally invasive and pose very little risk of damage to healthy ear tissue.